The invention pertains most broadly to semiconductor devices, and more particularly to non-reciprocal semiconductor devices usable as isolators.
Non-reciprocal electromagnetic devices have long been important. A non-reciprocal device is one whose propagation constant .gamma. differs depending upon the direction of electromagnetic propagation, and such non-reciprocal devices commonly use ferrite and external magnets to generate the requisite magnetic fields. Unfortunately, ferrites are not useful above approximately 100 GHz. As higher frequency applications become more important, there is a greater need for non-reciprocal devices that not only operate well at these frequencies but are compatible with the semiconductor technology pertinent to such higher frequency applications, most especially monolithic devices based on compound semiconductor materials combining elements from columns III and V of the periodic table (III-V semiconductors) and columns II and VI of the periodic table (II-VI semiconductors). Additionally, to be most practical such devices should operate effectively at room temperature.